implement VFIO_USER_REGION_READ/VFIO_USER_REGION_WRITE

Signed-off-by: Thanos Makatos <thanos.makatos@nutanix.com>

2 files changed, 103 insertions, 21 deletions

diff --git a/samples/client.c b/samples/client.c
index 91ab102..1a336373 100644
--- a/samples/client.c
+++ b/samples/client.c
@@ -36,6 +36,8 @@
 #include <errno.h>
 #include <sys/mman.h>
 #include <sys/eventfd.h>
+#include <time.h>
+#include <err.h>
 
 #include "../lib/muser.h"
 #include "../lib/muser_priv.h"
@@ -189,6 +191,46 @@ configure_irqs(int sock)
     return 0;
 }
 
+static int
+access_bar0(int sock)
+{
+    struct {
+        struct vfio_user_region_access region_access;
+        time_t t;
+    } __attribute__((packed)) data = {
+        .region_access = {
+            .region = LM_DEV_BAR0_REG_IDX,
+            .count = sizeof(data.t)
+        },
+        .t = time(NULL)
+    };
+    uint16_t msg_id = 1;
+    int ret = send_recv_vfio_user_msg(sock, msg_id, VFIO_USER_REGION_WRITE,
+                                      &data, sizeof data, NULL, 0, NULL, NULL, 0);
+    if (ret < 0) {
+        fprintf(stderr, "failed to write to BAR0: %s\n", strerror(-ret));
+        return ret;
+    }
+
+    printf("wrote to BAR0: %ld\n", data.t);
+
+    sleep(2);
+
+    msg_id++;
+
+    ret = send_recv_vfio_user_msg(sock, msg_id, VFIO_USER_REGION_READ,
+                                  &data.region_access, sizeof data.region_access,
+                                  NULL, 0, NULL, &data.t, sizeof data.t);
+    if (ret < 0) {
+        fprintf(stderr, "failed to read from BAR0: %s\n", strerror(-ret));
+        return ret;
+    }
+
+    printf("read from BAR0: %ld\n", data.t);
+
+    return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	int ret, sock;
@@ -205,7 +247,7 @@ int main(int argc, char *argv[])
 
     if (argc != 2) {
         fprintf(stderr, "usage: %s /path/to/socket\n", argv[0]);
-        return -1;
+        exit(EXIT_FAILURE);
     }
 
     if ((sock = init_sock(argv[1])) < 0) {
@@ -238,13 +280,11 @@ int main(int argc, char *argv[])
     nr_dma_regions = server_max_fds << 1;
 
     if ((fp = tmpfile()) == NULL) {
-        perror("failed to create DMA file");
-        return -1;
+        err(EXIT_FAILURE, "failed to create DMA file");
     }
 
     if ((ret = ftruncate(fileno(fp), nr_dma_regions * sysconf(_SC_PAGESIZE))) == -1) {
-        perror("failed to truncate file");
-        return -1;
+        err(EXIT_FAILURE,"failed to truncate file");
     }
 
     dma_regions = alloca(sizeof *dma_regions * nr_dma_regions);
@@ -296,6 +336,27 @@ int main(int argc, char *argv[])
         exit(EXIT_FAILURE);
     }
 
+    /*
+     * XXX VFIO_USER_REGION_READ and VFIO_USER_REGION_WRITE
+     *
+     * BAR0 in the server does not support memory mapping so it must be accessed
+     * via explicit messages.
+     */
+    ret = access_bar0(sock);
+    if (ret < 0) {
+        fprintf(stderr, "failed to access BAR0: %s\n", strerror(-ret));
+        exit(EXIT_FAILURE);
+    }
+
+    /*
+     * FIXME now that region read/write works, change the server implementation
+     * to trigger an interrupt after N seconds, where N is the value written to
+     * BAR0 by the client.
+     */
+
+    /* BAR1 can be memory mapped and read directly */
+    /* TODO implement the following: write a value in BAR1, a server timer will increase it every second (SIGALARM) */
+
     return 0;
 }
 
diff --git a/samples/server.c b/samples/server.c
index 6ebb65d..deb986b 100644
--- a/samples/server.c
+++ b/samples/server.c
@@ -41,6 +41,11 @@
 
 #include "../lib/muser.h"
 
+struct server_data {
+    time_t bar0;
+    uint8_t *bar1;
+};
+
 static void
 _log(void *pvt, lm_log_lvl_t lvl __attribute__((unused)), char const *msg)
 {
@@ -52,29 +57,35 @@ ssize_t
 bar0_access(void *pvt, char * const buf, size_t count, loff_t offset,
             const bool is_write)
 {
-    time_t t = time(NULL);
+    struct server_data *server_data = pvt;
 
     if (count != sizeof(time_t) || offset != 0) {
         errno = EINVAL;
         return -1;
     }
 
-    memcpy(buf, &t, count);
+    if (is_write) {
+        memcpy(&server_data->bar0, buf, count);
+    } else {
+        time_t delta = time(NULL) - server_data->bar0;
+        memcpy(buf, &delta, count);
+    }
 
     return count;
 }
 
-lm_ctx_t *lm_ctx;
+ssize_t
+bar1_access(void *pvt, char * const buf, size_t count, loff_t offset,
+            const bool is_write)
+{
+    assert(false);
+}
 
 bool irq_triggered = false;
 static void _sa_handler(int signum)
 {
     int _errno = errno;
     if (signum == SIGUSR1) {
-        /*
-         * FIXME not async-signal-safe becasue lm_irq_trigger prints to the log
-         */
-        lm_irq_trigger(lm_ctx, 0);
         irq_triggered = true;
     }
     errno = _errno;
@@ -92,7 +103,8 @@ int main(int argc, char *argv[])
     bool trans_sock = false, verbose = false;
     char opt;
     struct sigaction act = {.sa_handler = _sa_handler};
-    lm_ctx_t **_lm_ctx;
+    struct server_data server_data;
+    lm_ctx_t *lm_ctx;
 
     while ((opt = getopt(argc, argv, "v")) != -1) {
         switch (opt) {
@@ -100,8 +112,7 @@ int main(int argc, char *argv[])
                 verbose = true;
                 break;
             default: /* '?' */
-                fprintf(stderr, "Usage: %s [-d] <IOMMU group>\n", argv[0]);
-                exit(EXIT_FAILURE);
+                err(EXIT_FAILURE, "Usage: %s [-d] <IOMMU group>\n", argv[0]);
         }
     }
 
@@ -109,6 +120,11 @@ int main(int argc, char *argv[])
         err(EXIT_FAILURE, "missing MUSER device UUID");
     }
 
+    server_data.bar1 = malloc(sysconf(_SC_PAGESIZE));
+    if (server_data.bar1 == NULL) {
+        err(EXIT_FAILURE, "BAR1");
+    }
+
     lm_dev_info_t dev_info = {
         .trans = LM_TRANS_SOCK,
         .log = verbose ? _log : NULL,
@@ -119,16 +135,21 @@ int main(int argc, char *argv[])
                 .size = sizeof(time_t),
                 .fn = &bar0_access
             },
+            .reg_info[LM_DEV_BAR1_REG_IDX] = {
+                .flags = LM_REG_FLAG_RW,
+                .size = sysconf(_SC_PAGESIZE),
+                .fn = &bar1_access
+            },
             .irq_count[LM_DEV_INTX_IRQ_IDX] = 1,
         },
         .uuid = argv[optind],
         .unmap_dma = unmap_dma,
-        .pvt = &_lm_ctx
+        .pvt = &server_data
     };
 
     sigemptyset(&act.sa_mask);
     if (sigaction(SIGUSR1, &act, NULL) == -1) {
-        fprintf(stderr, "warning: failed to register signal handler: %m\n");
+        err(EXIT_FAILURE, "warning: failed to register signal handler: %m\n");
     }
 
     lm_ctx = lm_ctx_create(&dev_info);
@@ -136,16 +157,16 @@ int main(int argc, char *argv[])
         if (errno == EINTR) {
             goto out;
         }
-        fprintf(stderr, "failed to initialize device emulation: %m\n");
-        return -1;
+        err(EXIT_FAILURE, "failed to initialize device emulation: %m\n");
     }
-    _lm_ctx = &lm_ctx;
+
     do {
         ret = lm_ctx_drive(lm_ctx);
         if (ret == -EINTR) {
             if (irq_triggered) {
-                ret = 0;
                 irq_triggered = false;
+                lm_irq_trigger(lm_ctx, 0);
+                ret = 0;
             }            
         }
     } while (ret == 0);